Linear oligourethanes and polyurethanes having a defined structure, their preparation and their use

Abstract

In a process for preparing linear oligourethanes and polyurethanes by reacting 1 mole of a) diisocyanate with 1 mole of b) a compound having two groups which are reactive toward isocyanates, the functional groups of a) and/or b) have differing reactivities toward the functional groups of the other reactant and the reaction conditions are selected so that in each case only particular functional groups of a) and b) react with one another.

We claim:  
     
       1. A process for preparing linear oligourethanes and polyurethanes comprising: 
       1) forming a reaction product containing both one free isocyanate group and one free isocyanate reactive group by reacting a) at least one diisocyanate with b) at least one compound having two isocyanate reactive groups in a 1:1 molar ratio, wherein the isocyanate groups of a) and/or the isocyanate reactive groups of b) have differing reactivities toward the isocyanate reactive groups or the isocyanate groups, respectively, of the other reactant and wherein the free isocyanate reactive group, the free isocyanate group, or both are the least reactive of b) and a) respectively; and  
       2) reacting the product of step 1) intermolecularly to form a linear oligourethane or linear polyurethane.  
     
     
       2. A process for preparing linear oligourethanes and polyurethanes as claimed in  claim 1 , wherein the groups of higher reactivity in each of a) and b) react with one another. 
     
     
       3. A process for preparing linear oligourethanes and polyurethanes as claimed in  claim 1 , wherein the isocyanates having at least two isocyanate groups a) are selected from the group consisting of tolylene 2,4-diisocyanate, tolylene 2,6-diisocyanate, diphenylmethane 4,4′-diisocyanate, diphenylmethane 2,4′-diisocyanate, 3-alkyldiphenylmethane 4,4′-diisocyanate, where alkyl is from C 1  to C 10 , phenylene 1,3- and 1,4-diisocyanate, naphthylene 1,5-diisocyanate, tolidine diisocyanate, biphenyl diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, dodecane diisocyanate, lysine alkyl ester diisocyanate, where alkyl is from C 1  to C 10 , isophorone diisocyanate, 2-butyl-2-ethylpentamethylene diisocyanate, 2-isocyanatopropylcyclohexyl isocyanate, 4-methylcyclohexane 1,3-diisocyanate, dicyclohexylmethane 4,4′- and 2,4′-diisocyanate, 1,3- or 1,4-bis(isocyanatomethyl)cyclohexane and mixtures thereof. 
     
     
       4. A process for preparing linear oligourethanes and polyurethanes as claimed in  claim 1 , wherein the compounds having two groups which are reactive toward isocyanates are compounds b) having one primary and one secondary or tertiary hydroxyl group or one primary and one secondary or tertiary mercapto group, one primary and one secondary amino group, one hydroxyl group and one mercapto group, one mercapto group and one amino group or one hydroxyl group and one amino group in the molecule. 
     
     
       5. A linear oligourethane or polyurethane prepared as claimed in any of  claims 1  to  4 . 
     
     
       6. The process as claimed in  claim 1 , comprising the further step of reacting the product of step 2) with a polyether diol or a polyester diol to form a linear thermoplastic polyurethane. 
     
     
       7. The process as claimed in  claim 1 , comprising the further step of reacting the reaction product of step 2) with at least one of a fatty alcohol, a fatty amine, a monoalcohol containing at least one double bond, an acrylic acid, a dicarboxylic acid, an alkylene oxide, or mixtures thereof to form a polyurethane, a polyaddition polymer, or a polycondensation polymer. 
     
     
       8. The process as claimed in  claim 1 , comprising the further step of reacting the reaction product of step 2) with at least one of a polyfunctional alcohol, a polyfunctional amine, or a polyfunctional isocyanate to form at star-shaped or comb-shaped polymer. 
     
     
       9. The process as claimed in  claim 1 , comprising the further step of conducting step 1) at a temperature equal to or less than 0° C. 
     
     
       10. The process as claimed in  claim 9 , wherein the temperature is at or below −5° C. 
     
     
       11. The process as claimed in  claim 1 , wherein the reaction product formed in step 1) is elevated to a temperature of from 23° C. to 80° C. while conducting step 2). 
     
     
       12. The process as claimed in  claim 11 , wherein step 2) comprises the further step of raising the temperature of the reaction product formed in step 1) to a temperature of greater than 28° C. and adding a reaction catalyst. 
     
     
       13. The process as claimed in  claim 1 , wherein step 2) comprises the further step of raising the temperature of the reaction product formed in step 1) to a temperature of greater than 28° C. and adding a reaction catalyst.